Every time I render my sequence, the clips start glitching on playback. They jump all over the place and there are also constant flashes of red and green frames. It's only happened recently. The other day they were all fine after render. I don't know if this has got anything to do with it, but the clips are all quite long as they themselves are full finished sequences that I've exported and imported into this new project for the sake of compiling them all.